The pool store I go to is always pushing "PoolProof"
http://nisuscorp.com/pool-spa/products/poolproof which is basically
borate dissolved in a liquid. I was reading
http://www.poolspanews.com/efflorescence/borate-chemistry.aspx and it
seems to confirm the benefits of borate.

Of course anything sold for a pool has an enormous mark-up but borate
can be purchased at Walmart as 20 Mule Team Borax. I would need about 30
boxes (76 ounces each, $4) and about eight gallons of acid (about $5
each) to bring the Borate level up to 50ppm and the ph back down. To use
PoolProof would cost me about $300 if no acid was necessary (supposedly
PoolProof liquid is ph neutral) while pure borate powder raises the ph).

The benefits of a 50 ppm borate level are supposed to be a more stable
ph, less algae problems, and the ability to run the pool pump for fewer
hours. That last one could really make it pay for itself. Two hours less
a day of the pump running would probably save me $75 per month.

Anyone used PoolProof or other form of borate in their pool? I bought
all the borax that my local Walmart had in stock (eight boxes) and am
going to try it.